/* SDSLib, A C dynamic strings library
 *
 * Copyright (c) 2006-2012, Salvatore Sanfilippo <antirez at gmail dot com>
 * Copyright (c) 2014, Yinqiang <yinqiang.zhu at gmail dot com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include "sds.h"

/* Helper function for sdssplitargs() that returns non zero if 'c'
 * is a valid hex digit. */
static inline int is_hex_digit(char c) {
	return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f')
			|| (c >= 'A' && c <= 'F');
}

/* Helper function for sdssplitargs() that converts an hex digit into an
 * integer from 0 to 15 */
static inline int hex_digit_to_int(char c) {
	switch(c) {
		case '0': return 0;
		case '1': return 1;
		case '2': return 2;
		case '3': return 3;
		case '4': return 4;
		case '5': return 5;
		case '6': return 6;
		case '7': return 7;
		case '8': return 8;
		case '9': return 9;
		case 'a': case 'A': return 10;
		case 'b': case 'B': return 11;
		case 'c': case 'C': return 12;
		case 'd': case 'D': return 13;
		case 'e': case 'E': return 14;
		case 'f': case 'F': return 15;
		default: return 0;
	}
}

/*
 * 创建一个指定长度的 sds 
 * 如果给定了初始化值 init 的话，那么将 init 复制到 sds 的 buf 当中
 *
 * T = O(N)
 */
sds sdsnewlen(const void *init, size_t initlen) {
	struct sdshdr *sh;

	// 没有有init内容时，用‘\0’初始化buf内容
	sh = (struct sdshdr *)malloc(sizeof(struct sdshdr) + initlen + 1);
	if (init) {
		// sh = (struct sdshdr *)malloc(sizeof(struct sdshdr) + initlen + 1);
	} else {
		// sh = (struct sdshdr *)calloc(sizeof(struct sdshdr) + initlen + 1);
		memset(sh->buf, 0, initlen);
	}

	// 内存不足，分配失败
	if (sh == NULL) return NULL;

	sh->len = initlen;
	sh->free = 0;

	// 如果给定了 init 且 initlen 不为 0 的话
	// 那么将 init 的内容复制至 sds buf
	// O(N)
	if (initlen && init) {
		memcpy(sh->buf, init, initlen);
	}

	// 加上终结符
	sh->buf[initlen] = '\0';

	// 返回 buf 而不是整个 sdshdr
	return (char *)sh->buf;
}

/*
 * 根据给定初始化值 init ，创建 sds
 * 如果 init 为 NULL ，那么创建一个 buf 内只包含 \0 终结符的 sds
 *
 * T = O(N)
 */
sds sdsnew(const char *init) {
	size_t initlen = (init == NULL) ? 0 : strlen(init);
	return sdsnewlen(init, initlen);
}

/*
 * 创建一个只包含空字符串 "" 的 sds
 *
 * T = O(N)
 */
sds sdsempty() {
	return sdsnewlen("", 0);
}

/*
 * 释放 sds 所对应的 sdshdr 结构的内存。
 *
 * 如果 s 为 NULL ，那么不做动作。
 *
 * T = O(N)
 */
void sdsfree(sds s) {
	if (s == NULL) return;
	free(s - sizeof(struct sdshdr));
}

/* 
 * 复制给定 sds
 *
 * T = O(N)
 */
sds sdsdup(const sds s) {
	return sdsnewlen(s, sdslen(s));
}

/* Grow the sds to have the specified length. Bytes that were not part of
 * the original length of the sds will be set to zero. */
/*
 * 将 sds 的 buf 扩展至给定长度，无内容部分用 \0 来填充
 *
 * T = O(N)
 */
sds sdsgrowzero(sds s, const void *t, size_t len) {
	struct sdshdr *sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	size_t totlen, curlen = sh->len;

	// 现有长度比给定长度要大，无须扩展
	if (len <= curlen) {
		return s;
	}
	// 扩展 sds
	s = sdsMakeRoomFor(s, len - curlen);
	if (s == NULL) {
		return NULL;
	}

	/* Make sure added region doesn't contain garbage */
	// 使用 \0 来填充空位，确保空位中不包含垃圾数据
	sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	memset(s + curlen, 0, (len - curlen + 1)); /* also set trailing \0 byte */

	// 更新 len 和 free 属性
	totlen = sh->len + sh->free;
	sh->len = len;
	sh->free = totlen - sh->len;

	return s;
}

/*
 * 按长度 len 扩展 sds ，并将 t 拼接到 sds 的末尾
 *
 * T = O(N)
 */
sds sdscatlen(sds s, const char *t, size_t len) {
	struct sdshdr *sh;
	size_t curlen = sdslen(s);

	s = sdsMakeRoomFor(s, len);
	if (s == NULL) {
		return NULL;
	}

	memcpy(s + curlen, t, len);

	// 更新 len 和 free 属性
	sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	sh->len = curlen + len;
	sh->free = sh->free - len;

	// 终结符
	s[curlen + len] = '\0';

	return s;
}

/*
 * 将一个 char 数组拼接到 sds 末尾 
 *
 * T = O(N)
 */
sds sdscat(sds s, const char *t) {
	return sdscatlen(s, t, strlen(t));
}

/*
 * 拼接两个 sds 
 *
 * T = O(N)
 */
sds sdscatsds(sds s, const sds t) {
	return sdscatlen(s, t, sdslen(t));
}

/*
 * 将一个 char 数组的前 len 个字节复制至 sds
 * 如果 sds 的 buf 不足以容纳要复制的内容，
 * 那么扩展 buf 的长度，让 buf 的长度大于等于 len 。
 *
 * T = O(N)
 */
sds sdscpylen(sds s, const char *t, size_t len) {
	struct sdshdr *sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));

	// 是否需要扩展 buf ?
	size_t totlen = sh->free + sh->len;
	if (totlen < len) {
		// 扩展 buf 长度，让它的长度大于等于 len
		// 具体的大小请参考 sdsMakeRoomFor 的注释
		// T = O(N)
		s = sdsMakeRoomFor(s, len - sh->len);
		if (s == NULL) {
			return NULL;
		}
		sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
		totlen = sh->free + sh->len;
	}

	memcpy(s, t, len);
	s[len] = '\0';

	sh->len = len;
	sh->free = totlen - len;

	return s;
}

/*
 * 将一个 char 数组复制到 sds
 */
sds sdscpy(sds s, const char *t) {
	return sdscpylen(s, t, strlen(t));
}

sds sdscatvprintf(sds s, const char *fmt, va_list ap) {
	va_list cpy;
	char *buf, *t;
	size_t buflen = 16;

	while (1) {
		buf = (char *)malloc(buflen);
		if (buf == NULL) {
			return NULL;
		}
		buf[buflen - 2] = '\0';
		va_copy(cpy, ap);
		vsnprintf(buf, buflen, fmt, cpy);
		if (buf[buflen - 2] != '\0') {
			free(buf);
			buflen *= 2;
			continue;
		}
		break;
	}
	t = sdscat(s, buf);
	free(buf);
	return t;
}

sds sdscatprintf(sds s, const char *fmt, ...) {
	va_list ap;
	char *t;
	va_start(ap, fmt);
	t = sdscatvprintf(s, fmt, ap);
	va_end(ap);
	return t;
}

sds sdsrange(sds s, int start, int end) {
	struct sdshdr *sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	size_t newlen, len = sdslen(s);

	if (len == 0) {
		return s;
	}
	if (start < 0) {
		start = len + start;
		if (start < 0) {
			start = 0;
		}
	}
	if (end < 0) {
		end = len + end;
		if (end < 0) {
			end = 0;
		}
	}
	newlen = (start > end) ? 0 : (end - start) + 1;
	if (newlen != 0) {
		if (start >= (signed)len) {
			newlen = 0;
		} else if (end >= (signed)len) {
			end = len - 1;
			newlen = (start > end) ? 0 : (end - start) + 1;
		}
	} else {
		start = 0;
	}
	if (start && newlen) {
		memmove(sh->buf, sh->buf + start, newlen);
	}
	sh->buf[newlen] = 0;
	sh->free = sh->free + (sh->len - newlen);
	sh->len = newlen;
	return s;
}


void sdsupdatelen(sds s) {
	struct sdshdr *sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	int reallen = strlen(s);
	sh->free += (sh->len - reallen);
	sh->len = reallen;
}


void sdsclear(sds s) {
	struct sdshdr *sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	sh->free += sh->len;
	sh->len = 0;
	sh->buf[0] = '\0';
}


int sdscmp(const sds s1, const sds s2) {
	size_t l1, l2, minlen;
	int cmp;

	l1 = sdslen(s1);
	l2 = sdslen(s2);
	minlen = (l1 < l2) ? l1 : l2;
	cmp = memcmp(s1, s2, minlen);
	if (cmp == 0) {
		return l1 - l2;
	}
	return cmp;
}


void sdsfreespliters(sds *tokens, int count) {
	if (!tokens) {
		return;
	}
	while (count --) {
		sdsfree(tokens[count]);
	}
	free(tokens);
}

/* Split 's' with separator in 'sep'. An array
 * of sds strings is returned. *count will be set
 * by reference to the number of tokens returned.
 *
 * On out of memory, zero length string, zero length
 * separator, NULL is returned.
 *
 * Note that 'sep' is able to split a string using
 * a multi-character separator. For example
 * sdssplit("foo_-_bar","_-_"); will return two
 * elements "foo" and "bar".
 *
 * This version of the function is binary-safe but
 * requires length arguments. sdssplit() is just the
 * same function but for zero-terminated strings.
 */
sds *sdssplitlen(const char *s, int len, char const *sep, int seplen, int *count) {
	int elements = 0, slots = 5, start = 0, j;
	sds *tokens;

	if (seplen < 1 || len < 0) {
		return NULL;
	}

	tokens = (sds *)malloc(sizeof(sds) * slots);
	if (tokens == NULL) {
		return NULL;
	}

	if (len == 0) {
		*count = 0;
		return tokens;
	}
	for (j = 0; j < (len - (seplen - 1)); j++) {
		/* make sure there is room for the next element and the final one */
		if (slots < elements + 2) {
			sds *newtokens;

			slots *= 2;
			newtokens = (sds *)realloc(tokens, sizeof(sds) * slots);
			if (newtokens == NULL) {
				goto cleanup;
			}
			tokens = newtokens;
		}
		/* search the separator */
		if ((seplen == 1 && *(s + j) == sep[0])
			|| (memcmp(s + j, sep, seplen) == 0))
		{
			tokens[elements] = sdsnewlen(s + start, j - start);
			if (tokens[elements] == NULL) {
				goto cleanup;
			}
			elements ++;
			start = j + seplen;
			j = j + seplen - 1;
		}
	}
	/* Add the final element. We are sure there is room in the tokens array. */
	tokens[elements] = sdsnewlen(s + start, len - start);
	if (tokens[elements] == NULL) {
		goto cleanup;
	}
	elements ++;
	*count = elements;
	return tokens;

cleanup:
	{
		int i;
		for (i = 0; i < elements; i++) {
			sdsfree(tokens[i]);
		}
		free(tokens);
		*count = 0;
		return NULL;
	}
}

/* Split a line into arguments, where every argument can be in the
 * following programming-language REPL-alike form:
 *
 * foo bar "newline are supported\n" and "\xff\x00otherstuff"
 *
 * The number of arguments is stored into *argc, and an array
 * of sds is returned. The caller should sdsfree() all the returned
 * strings and finally zfree() the array itself.
 *
 * Note that sdscatrepr() is able to convert back a string into
 * a quoted string in the same format sdssplitargs() is able to parse.
 */
sds *sdssplitargs(const char *line, int *argc) {
	const char *p = line;
	char *current = NULL;
	char **vector = NULL;

	*argc = 0;
	while (1) {
		/* skip blanks */
		while (*p && isspace((int)*p)) {
			p ++;
		}
		if (*p) {
			/* get a token */
			int inq = 0;  /* set to 1 if we are in "quotes" */
			int insq = 0; /* set to 1 if we are in 'single quotes' */
			int done = 0;

			if (current == NULL) {
				current = sdsempty();
			}
			while (!done) {
				if (inq) {
					if (*p == '\\' && *(p + 1) == 'x'
						&& is_hex_digit(*(p + 2))
						&& is_hex_digit(*(p + 3)))
					{
						unsigned char byte;

						byte = (hex_digit_to_int(*(p + 2)) * 16)
								+ hex_digit_to_int(*(p + 3));
						current = sdscatlen(current, (char *)&byte, 1);
						p += 3;
					} else if (*p == '\\' && *(p + 1)) {
						char c;

						p ++;
						switch (*p) {
							case 'n': c = '\n'; break;
							case 'r': c = '\r'; break;
							case 't': c = '\t'; break;
							case 'b': c = '\b'; break;
							case 'a': c = '\a'; break;
							default: c = *p; break;
						}
						current = sdscatlen(current, &c, 1);
					} else if (*p == '"') {
						/* closing quote must be followed by a space or
                         * nothing at all. */
						if (*(p + 1) && !isspace((int)*(p + 1))) {
							goto err;
						}
						done = 1;
					} else if (!(*p)) {
						/* unterminated quotes */
						goto err;
					} else {
						current = sdscatlen(current, p, 1);
					}
				} else if (insq) {
					if (*p == '\\' && *(p + 1) == '\'') {
						p ++;
						current = sdscatlen(current, "'", 1);
					} else if (*p == '\'') {
						/* closing quote must be followed by a space or
                         * nothing at all. */
						if (*(p + 1) && !isspace((int)*(p + 1))) {
							goto err;
						}
						done = 1;
					} else if (!(*p)) {
						/* unterminated quotes */
						goto err;
					} else {
						current = sdscatlen(current, p, 1);
					}
				} else {
					switch (*p) {
						case ' ':
						case '\n':
						case '\r':
						case '\t':
						case '\0':
							done = 1;
							break;
						case '"':
							inq = 1;
							break;
						case '\'':
							insq = 1;
							break;
						default:
							current = sdscatlen(current, p, 1);
							break;
					}
				}
				if (*p) {
					p ++;
				}
			}
			/* add the token to the vector */
			vector = (char **)realloc(vector, ((*argc) + 1) * sizeof(char *));
			vector[*argc] = current;
			(*argc) ++;
			current = NULL;
		} else {
			return vector;
		}
	}

err:
	{
		while ((*argc) --) {
			sdsfree(vector[*argc]);
		}
		free(vector);
		if (current) {
			sdsfree(current);
		}
		return NULL;
	}
}

void sdssplitargs_free(sds *argv, int argc) {
	int j;

	for (j = 0; j < argc; j++) {
		sdsfree(argv[j]);
	}
	free(argv);
}


sds sdstrim(sds s, const char *cset) {
	struct sdshdr *sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	char *start, *end, *sp, *ep;
	size_t len;

	sp = start = s;
	ep = end = s + sdslen(s) - 1;
	while (sp <= end && strchr(cset, *sp)) {
		sp ++;
	}
	while (ep > start && strchr(cset, *ep)) {
		ep --;
	}
	len = (sp > ep) ? 0 : ((ep - sp) + 1);
	if (sh->buf != sp) {
		memmove(sh->buf, sp, len);
	}
	sh->buf[len] = '\0';
	sh->free = sh->free + (sh->len - len);
	sh->len = len;
	return s;
}

/*
 * 将给定 sds 中的字符全部转为小写
 */
void sdstolower(sds s) {
	int len = sdslen(s), j;

	for (j = 0; j < len; j++) {
		s[j] = tolower((int)s[j]);
	}
}

/*
 * 将给定 sds 中的字符全部转为大写
 */
void sdstoupper(sds s) {
	int len = sdslen(s), j;

	for (j = 0; j < len; j++) {
		s[j] = toupper((int)s[j]);
	}
}

sds sdsfromlonglong(long long value) {
	char buf[32], *p;
	unsigned long long v;

	v = (value < 0) ? -value : value;
	p = buf + 31; /* point to the last character */
	do {
		*p = '0' + (v % 10);
		v /= 10;
		p --;
	} while (v);
	if (value < 0) {
		*p = '-';
		p --;
	}
	p ++;
	return sdsnewlen(p, 32 - (p - buf));
}


sds sdscatrepr(sds s, const char *p, size_t len) {
	s = sdscatlen(s, "\"", 1);
	while (len --) {
		switch (*p) {
			case '\\':
			case '"':
				s = sdscatprintf(s, "\\%c", *p);
				break;
			case '\n': s = sdscatlen(s, "\\n", 2); break;
			case '\r': s = sdscatlen(s, "\\r", 2); break;
			case '\t': s = sdscatlen(s, "\\t", 2); break;
			case '\a': s = sdscatlen(s, "\\a", 2); break;
			case '\b': s = sdscatlen(s, "\\b", 2); break;
			default:
				if (isprint((int)*p)) {
					s = sdscatprintf(s, "%c", *p);
				} else {
					s = sdscatprintf(s, "\\x%02x", (unsigned char)*p);
				}
				break;
		}
		p ++;
	}
	return sdscatlen(s, "\"", 1);
}

/* Modify the string substituting all the occurrences of the set of
 * characters specifed in the 'from' string to the corresponding character
 * in the 'to' array.
 *
 * For instance: sdsmapchars(mystring, "ho", "01", 2)
 * will have the effect of turning the string "hello" into "0ell1".
 *
 * The function returns the sds string pointer, that is always the same
 * as the input pointer since no resize is needed. */
sds sdsmapchars(sds s, const char *from, const char *to, size_t setlen) {
	size_t j, i, l = sdslen(s);

	for (j = 0; j < l; j++) {
		for (i = 0; i < setlen; i++) {
			if (s[j] == from[i]) {
				s[j] = to[i];
				break;
			}
		}
	}
	return s;
}


/* Low level functions exposed to the user API */

sds sdsMakeRoomFor(sds s, size_t addlen) {
	struct sdshdr *sh, *newsh;
	size_t free = sdsavail(s);
	size_t len, newlen;

	if (free >= addlen) {
		return s;
	}
	sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	len = sdslen(s);
	newlen = (len + addlen);
	if (newlen < SDS_MAX_PREALLOC) {
		newlen *= 2;
	} else {
		newlen += SDS_MAX_PREALLOC;
	}
	newsh = (struct sdshdr *)realloc(sh, sizeof(struct sdshdr) + newlen + 1);
	if (newsh == NULL) {
		return NULL;
	}
	newsh->free = newlen - len;
	return newsh->buf;
}

void sdsIncrLen(sds s, int incr) {
	struct sdshdr *sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	assert(sh->free >= incr);
	sh->len += incr;
	sh->free -= incr;
	assert(sh->free >= 0);
	s[sh->len] = '\0';
}

sds sdsRemoveFreeSpace(sds s) {
	struct sdshdr *sh;

	sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	sh = (struct sdshdr *)realloc(sh, sizeof(struct sdshdr) + sh->len + 1);
	sh->free = 0;

	return sh->buf;
}

size_t sdsAllocSize(sds s) {
	struct sdshdr *sh = (struct sdshdr *)(s - (sizeof(struct sdshdr)));
	return sizeof(*sh) + sh->len + sh->free + 1;
}
